Application of a fluid polymer coating onto a substrate is one necessary process in the manufacture of a great variety of electronic substrate components. As an example, a photoresist composition is applied to a substrate to fabricate glassmasters for the production of compact discs, semiconductor integrated circuits and other products. Typical liquid-type photoresist compositions used to coat these devices comprise a polymer and photosensitive compound dissolved or suspended in an organic solvent.
Other processing steps may be needed in addition to the polymeric coating. For example, in the production of a compact disc glassmaster, the glass surface of the substrate is thoroughly cleaned and dried prior to application of the photoresist coating. Glass, however, has a high affinity to water and a molecular layer of water will adhere to the surface. Water has a tendency to repel photoresist compositions when they are applied onto a water containing surface. In this case an intermediate adhesive layer is required which has a high affinity to the glass surface and to which the subsequently applied polymeric material has a reasonable affinity. The adhesive layer is preliminarily deposited on the surface of the substrate in an organic solvent prior to deposition of photoresist compositions. Additional layers of appropriate materials may be deposited on this substrate. Like the compact disc manufacturing industry, the production of semiconductors for certain applications requires a highly polished surface to be maintained prior to coating with a photoresist. A barrier layer is generally applied between the substrate, for example, silicon, alumina or quartz, and the polymeric photoresist.
Various methods for curing polymer and more specifically photoresist coatings, employing temperature or time control heating systems to fix the coating on the substrate are currently used. These curing/drying procedures are not always sufficiently effective in removing all the solvents in these coating processes. It is believed that the uncured or partially cured polymer coatings may cause failure of the substrate during additional processing steps or utilization of the product which is carried out after this development operation. Accordingly, there is a need for an improved curing system which more precisely monitors the curing process.